1. Field of the Invention
The present invention relates to a rotary atomizer which atomizes paint so as to coat a target with the paint. In particular, the present invention relates to a rotary atomizer which can serve as both a bell spray and a gun spray.
2. Related Art
A rotary atomizer expands fluid paint on an inner surface of a rotating bell cup so as to atomize the paint by the centrifugal force, and electrifies the paint by static high voltage impressed on an atomizing head or the like and forms an electrostatic field formed between the atomizer and the grounded target, thereby performing electrostatic coating.
There is a well-known conventional rotary atomizer having a cup-like shaped head which is controlled in rotary speed for switching its usage between rotary atomizing mode and air atomizing mode (as disclosed in the Japanese Patent Hei. 4-56674).
There is also a well-known conventional rotary atomizer which can adjust the amount of sprayed air for regulating width of a spray pattern (as disclosed in the Japanese Patent Laid Open Gazette Hei. 10-71345).
A bell-type rotary atomizer makes a spray pattern of a diameter from about 200 to about 1000 mm by the centrifugal force of the rotating bell cup and the electrostatic repulsion among electrostatically charged paint particles. Such a large spray pattern has the difficulty of closely coating targets such as small local points or small products. Even if the charge of static electricity is cut off for the purpose of obtaining a diametrically small spray pattern, the spray pattern is still large because of the centrifugal force and the cutting-off of the static electricity lowers the paint transfer efficiency steeply against the intention.
On the other hand, with regard to workability of coating, since a sufficiently small spray pattern is not obtained with the bell-type rotary atomizer, a hand spray gun can be possibly required for finishing a local point or a small product, thereby causing gross decline of workability and rise of cost.